Recent patents of dipeptidyl peptidase IV inhibitors.

INTRODUCTION: The serine exopeptidase DPP IV is a dual protein able to work as an enzyme and an interacting protein. The incretin molecules glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) are hydrolyzed by DPP IV into inactive forms, which are unable to promote insulin secretion. Therefore, DPP IV is a validated target for the treatment of type 2 diabetes mellitus (T2DM), and a number of inhibitors have been reported in the literature as antidiabetic drugs. AREAS COVERED: DPP IV inhibitor patents from 2006 are included in this review. Documents are classified into chemical groups depending on the main claim. Groups are: i) pyrrolidines and thiazolidines; ii) cyclohexanes, piperidines, piperazines, pyridines and pyrimidines; iii) fused 5-carbon cycles; iv) pyridine, pyrimidine and pyrazine-based bicyclic structures; v) indoles, condensed-imidazoles and xanthines; vi) pyrido-pyrimidines, quinolones, isoquinolines, quinozalines, quinoxalines, naphthyridines, quinolones and quinazolinones; vii) benzoquinolizines, fused aminopiperidines and fused triazoles; viii) other heterocyclic structures and ix) peptidomimetics. EXPERT OPINION: Research in finding new DPP IV inhibitors is intense, despite the number of reported molecules. This is mainly because marketed compounds have been approved in the last 5 years and long-term side effects have not been detected. The perfect inhibitor for the T2DM treatment would therefore be a molecule that inhibits GLP-1 and GIP degradation by DPP IV, but does not affect the activity of the protease in other substrates, nor disturbs the communication of DPP IV with other proteins.